If you want the most tire that will fit a QL without rubbing, that seems to be 275/55/20 on OEM wheels or perhaps 275/60/18 as 275/65s may be a bit too tall. They are a tight fit, however, and may just touch the felt liner under some extreme conditions (full lock park height). A few claim to be running both + 34 offset 20x9 wheels and str8 wheels with 285/50/20 tires with no rubbing issues at all QL heights.